The offer comes amid rumours that the Government in Whitehall is preparing to announce it will not back the UK’s first major tidal lagoon power project because it fails to meet value for money targets.

Yesterday the Government announced it would save the £14bn Wylfa nuclear power station project with a public funding package of around £5bn, after builder Hitachi warned it would walk away from the Anglesey scheme unless risk was shared on the project.

The Swansea Bay renewable energy project was backed in January 2017 by a UK government-commissioned report published by former energy minister Charles Hendry.

This concluded that tidal lagoons could play a cost-effective role in the UK’s energy mix.

But the Government has delayed taking a decision amid serious concerns about value for money.

Keith Clarke, chairman, Tidal Lagoon (Swansea Bay), said: “Once again we thank the First Minister for his particularly timely initiative.

“We look forward to seeing the UK Government’s positive response to a proposed joint deal on these terms.

“The proposal for a joint deal with this structure is extremely constructive, we are eager to engage on it with all parties and it is a proposal we’d be delighted to take to our board.”

If it is built, the scheme would be the world’s first tidal lagoon power project providing electricity for around 155,000 homes and sustaining 2,200 construction jobs..